The spinal column of bones is a highly complex anatomical structure that includes over 20 bones coupled to one another, housing and protecting critical elements of the nervous system having innumerable peripheral nerves and circulatory bodies in close proximity. Despite its complexity, the spine is a highly flexible structure, capable of a high degree of curvature and twist in nearly every direction. The more than 20 discrete bones of an adult human spinal column are anatomically categorized as one of four classifications—cervical, thoracic, lumbar, or sacral—and are coupled together sequentially to one another by a tri-joint complex that consists of an anterior disc and two posterior facet joints. The anterior discs of adjacent bones are cushioned by cartilage spacers referred to as intervertebral discs or vertebrae. The cervical portion of the spine comprises the top of the spine up to the base of the skull and includes the first seven vertebrae. The intermediate 12 bones are thoracic vertebrae, and connect to the lower spine comprising the 5 lumbar vertebrae. The base of the spine comprises sacral bones, including the coccyx. With its complex nature, however, there is also an increased likelihood that surgery may be needed to correct one or more spinal pathologies.
Various systems exist for connecting fastener elements (e.g., pedicle screws) to bones for the purpose of vertebral fixation. Such systems may use a plurality of bone screws fitted in tulip heads where the tulip heads may be aligned using a mounting rod. Set screws may be disposed above the mounting rod and fastened against threads in saddles of the tulip heads. Such fastening may secure components within the saddle and provide overall stability to a bone screw system. In order to fasten a set screw, the set screw may need to be lowered through a channel or spacing between removable arms of the tulip head. Once lowered, a counter-torque wrench system may be used to reach the set screw at a distal end of the removable arms and then be used to fasten a set screw into the threads of the saddle.
For surgical proceedings, the size of incisions made in a patient may be dictated by the size or width of the components that need to be inserted into a patient's body and the size of the tools required to install such components. Accordingly, a need has arisen for an improved counter-torque wrench that advantageously provides a more minimally invasive system that allows for smaller incisions to be made during surgery. Therefore, a smaller, more minimally invasive counter torque wrench is desired.